1. Field of the Invention
The present invention relates to a print head for printing an image on a print medium when it is mounted on and driven by a printer apparatus main body, and a printer apparatus using the same.
2. Description of the Related Art
FIGS. 2 to 4 show the arrangements of conventional print heads. In a print head shown in FIG. 2, electricity-to-heat converters 2 such as heating resistors, terminals 17a, and wiring lines 16 for connecting the terminals 17a and the electricity-to-heat converters 2 are arranged on a heater board 1a. In a print head shown in FIG. 3, a diode matrix 18 is arranged between terminals 17b and wiring lines 16, so that driving signals from an external circuit can be received via a smaller number of terminals 17b than the number of terminals 17a in FIG. 2. In the case of a print head shown in FIG. 4, a driver 3 is arranged in a heater board 1c, and the driver 3 and electricity-to-heat converters 2 are directly connected by wiring lines 16. Print data for driving the electricity-to-heat converters 2 to generate heat are input from terminals 17c to shift registers 20. In this case, the number of terminals 17c can be smaller than the numbers of terminals 17a and 17b on the above-mentioned heater boards 1a and 1b.
FIGS. 5 and 6 show the arrangements of printer apparatuses which adopt such print heads.
FIG. 5 is a block diagram showing a connection between the arrangement of a printer apparatus adopting the print head shown in FIG. 2 or 3, and a host computer 30.
Referring to FIG. 5, the host computer 30 supplies print information to an input/output interface (I/F) 8 in a printer apparatus 21. The print information is supplied to a microprocessor (MPU) 28, and is converted by the MPU 28 into predetermined print information under the control of a program stored in a memory (not shown). The converted print information is supplied to the heater board 1a or 1b via a driver 27. The driver 27 drives the electricity-to-heat converters 2 of a head 22 to discharge ink droplets, thereby printing an image on a print medium. The print head 22 comprises, e.g., a temperature control heater 24 for increasing the temperature of the print head 22, a temperature sensor 25 for detecting the head temperature, and the like in addition to the heater board 1a or 1b, and is controlled to improve print quality using the MPU 28 and the driver 27.
FIG. 6 is a block diagram showing a connection between the arrangement of a printer apparatus which adopts a print head 22 shown in FIG. 4 and the host computer 30. In the print head 22 shown in FIG. 6, the heater board 1c builds in the driver 27 in addition to the electricity-to-heat converters 2. A power supply 26 is connected to the driver 27, and print data is supplied to the electricity-to-heat converters 2 via the driver 27.
The above-mentioned conventional arrangements suffer the following problems to be solved.
The print head shown in FIG. 2 requires the terminals 17a and the wiring lines in correspondence with the number of electricity-to-heat converters. Therefore, the board size of the heater board 1a increases, and the wiring lines in the printer apparatus 21 increase in number and are complicated, resulting in an increase in cost.
In the case of the print head shown in FIG. 3, when the diode matrix 18 (m.times.p) is used, the number of electrical contacts of the terminals 17b and the number of wiring lines can be (m+p) since the number n of the electricity-to-heat converters is given by n=m.times.p. However, in this case, since a matrix driving method is adopted, the degree of freedom in a method of driving nozzles is lowered.
In the case of the print head shown in FIG. 4, the number of electrical contacts of the terminals 17c and the number of wiring lines are smaller than those of the above-mentioned print heads. However, since this head adopts a serial data transfer method using the shift registers 20, print data must be temporarily converted into serial data in the printer apparatus 21. Therefore, the loads on software and hardware increase, resulting in a decrease in transfer rate of print data and an increase in hardware cost.
Furthermore, in the conventional printer apparatus as shown in FIGS. 5 and 6, it is required to provide an interface 8 for inputting information transferred from the host computer 30, a microprocessor 28 for processing the information, and a signal path (such as a cable) for transferring a signal to a driving head in the printer apparatus. Furthermore, another signal path for transferring the information to the microprocessor 28 to feedback the temperature information detected by the temperature sensor 25 of the print head is also required. Thus, problems arise in complication in the circuit constitution, increase in the circuit scale of the entire apparatus, and increase in cost due to the increase of the number of assembling steps.